P080B: Upshift/Skip Shift Solenoid Control Circuit Range/Performance

What does P080B mean?

GM's skip-shift (CAGS) on manual gearboxes such as the T56 and TR6060 uses an engine-module solenoid that, at light load, blocks the way from 1st into 2nd so the driver shifts 1 to 4; the 1-4 lamp shows it (P0804). The engine module drives the solenoid with a low-side driver; P0803 is the open circuit. P080B would be the range or performance fault of this circuit: electrically plausible, but outside the expected range for the command – for example a coil resistance outside its window, a partial short or contact resistance. No manufacturer document available to us uses it: GM's tables from 2006 to 2019 check the solenoid only electrically (P0803 open, P080C short to ground, P080D short to positive). CARB requires a functional check of outputs where feasible. The lockout may then work unreliably.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine lamp (depends on manufacturer)
• 1-4 lockout works not at all or only sometimes
• Otherwise no change in driving

Common causes

• Medium Solenoid coil with shorted turns or resistance out of range
• Medium Retrofitted skip-shift eliminator with the wrong value
• Medium Corroded connector at the gearbox (contact resistance)
• Low Control module or software

Likelihood is a general estimate across vehicles; your make and model may differ.